feat: added day 17 part 1 and 2

Signed-off-by: Louis Vallat <contact@louis-vallat.dev>

.gitea/workflows/build_and_run.yml

@@ -11,7 +11,7 @@ jobs:
     name: Challenge for day
     strategy:
       matrix:
-        day_number: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]
+        day_number: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]
     runs-on: rust-bookworm
     steps:
       - name: Check out repository code

day17/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "day17"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

day17/src/main.rs

@@ -0,0 +1,132 @@
+use std::collections::HashSet;
+use std::{env, fs};
+
+#[derive(Debug, Clone, Copy, Eq, PartialEq, Hash, PartialOrd)]
+enum Instruction {
+    Adv(u64), // Division           A = A / 2^x
+    Bdv(u64), // Division           B = A / 2^x
+    Cdv(u64), // Division           C = A / 2^x
+    Bst(u64), // Combo % 8          B = x % 8
+    Jnz(u64), // Jump if not 0.     if A != 0 { jump to x }
+    Out(u64), // Print x % 8        echo(x % 8)
+    Bxl(u64), // Bitwise XOR        B = B XOR x
+    Bxc,      // Bitwise XOR        B = B XOR C
+}
+
+fn read_input(path: &str) -> String {
+    fs::read_to_string(path).expect("Cannot read file.")
+}
+
+fn parse_input(input: &str) -> (Vec<Instruction>, Vec<String>, u64, u64, u64) {
+    let mut instructions = Vec::new();
+
+    let mut lines = input.lines();
+    let a = lines.next().unwrap()[12..].parse::<u64>().unwrap();
+    let b = lines.next().unwrap()[12..].parse::<u64>().unwrap();
+    let c = lines.next().unwrap()[12..].parse::<u64>().unwrap();
+
+    lines.next();
+    let raw_program = lines.next().unwrap()[9..]
+        .split(',')
+        .map(|s| s.to_string())
+        .collect::<Vec<String>>();
+    for a in raw_program.chunks(2) {
+        let operand = a[1].parse().unwrap();
+        instructions.push(match a[0].as_str() {
+            "0" => Instruction::Adv(operand),
+            "1" => Instruction::Bxl(operand),
+            "2" => Instruction::Bst(operand),
+            "3" => Instruction::Jnz(operand),
+            "4" => Instruction::Bxc,
+            "5" => Instruction::Out(operand),
+            "6" => Instruction::Bdv(operand),
+            "7" => Instruction::Cdv(operand),
+            _ => unreachable!(),
+        })
+    }
+
+    (instructions, raw_program, a, b, c)
+}
+
+fn get_value_for_operand(operand: u64, a: u64, b: u64, c: u64) -> u64 {
+    match operand {
+        0..=3 => operand,
+        4 => a,
+        5 => b,
+        6 => c,
+        _ => unreachable!(),
+    }
+}
+
+fn run_program(instructions: &Vec<Instruction>, mut a: u64, mut b: u64, mut c: u64) -> Vec<String> {
+    let mut output = Vec::new();
+    let mut pc = 0;
+    while pc < instructions.len() {
+        let instruction = instructions[pc];
+        match instruction {
+            Instruction::Adv(x) => a = a / 2_u64.pow(get_value_for_operand(x, a, b, c) as u32),
+            Instruction::Bdv(x) => b = a / 2_u64.pow(get_value_for_operand(x, a, b, c) as u32),
+            Instruction::Cdv(x) => c = a / 2_u64.pow(get_value_for_operand(x, a, b, c) as u32),
+            Instruction::Bst(x) => b = get_value_for_operand(x, a, b, c) % 8,
+            Instruction::Jnz(x) => {
+                if a != 0 {
+                    pc = x as usize
+                }
+            }
+            Instruction::Out(x) => output.push((get_value_for_operand(x, a, b, c) % 8).to_string()),
+            Instruction::Bxl(x) => b = b ^ x,
+            Instruction::Bxc => b = b ^ c,
+        }
+        match instruction {
+            Instruction::Jnz(_) => {
+                if a == 0 {
+                    pc += 1
+                }
+            }
+            _ => pc += 1,
+        }
+    }
+    output
+}
+
+fn best_quine(instruction: &Vec<Instruction>, raw_program: &Vec<String>) -> u64 {
+    let mut valid = HashSet::new();
+
+    let mut seen = HashSet::new();
+    let mut queue = vec![0];
+    while let Some(mut possibility) = queue.pop() {
+        possibility <<= 3;
+        for x in possibility..(possibility + 8) {
+            let output = run_program(instruction, x, 0, 0);
+            if !output.is_empty()
+                && *output.first().unwrap() == raw_program[raw_program.len() - output.len()]
+            {
+                if raw_program.len() == output.len() {
+                    valid.insert(x);
+                } else if !seen.contains(&x) {
+                    seen.insert(x);
+                    queue.push(x);
+                }
+            }
+        }
+    }
+
+    *valid.iter().min().unwrap_or(&0)
+}
+
+fn main() {
+    let args: Vec<String> = env::args().collect();
+    for arg in args.iter().skip(1) {
+        let input = read_input(&arg);
+        let (instructions, raw_program, a, b, c) = parse_input(&input);
+        println!("[{}]", &arg);
+        println!(
+            "\t[Part 1] => Answer is '{}'.",
+            run_program(&instructions, a, b, c).join(",")
+        );
+        println!(
+            "\t[Part 2] => Answer is '{}'.",
+            best_quine(&instructions, &raw_program)
+        );
+    }
+}